Question

Help please:)

Answer 1

well since the speed is in mph, you first need to convert the 12 minutes into hours

Answer 2

okie, how do i do that?

Answer 3

12/60

Answer 4

well we know 60 minutes are in 1 hours, so you do a unit conversion

or solve the ratio

\[\frac{1 hour}{60 minutes}=\frac{x hours}{12 minutes}\]

and yes 12/60

Answer 5

ok

Answer 6

which is .2 hours

now onto the actual question

the truck is driving at 60 mph

12 minutes later, a car enters the high way driving at 72 mph

so lets consider the entrance of the highway, distance 0 or x=0

so when the car enters the highway, how far has the truck driven?

Answer 7

i think i figured it out. is it 65 mph? o.0

Answer 8

nevermind >.<

Answer 9

you're looking for a time it takes to pass, 65mph is a speed

Answer 10

now answer my question

Answer 11

if the truck is driving at 60 mph for 12 minutes or .2 hours, how far did the truck drive

remember d=vt

Answer 12

im not sure, i just confused myself.

Answer 13

you're going 60 mph, this is a velocity "v", for .2 hours, this is a time "t"

what is "d"?

Answer 14

12

Answer 15

right?

Answer 16

right, when the car enters the highway, the truck will have already driven 12 miles

Answer 17

does this make sense?

Answer 18

yes

Answer 19

im writing down so i have for my notes

Answer 20

ok now bear with me because this might get really confusing

we want to know when the car passes the truck, this moment is when the distance the car has travelled is equal to the distance the truck has travelled

this time, we will call "t" and it will be in hours

now, the distance the car travels can be written as 72*t=d

now we look at the distance of the truck at time t

since the truck has already driven 12 miles, and is still driving at 60mph

the total distance the truck has travelled can be written as
d=12+60t

Answer 21

35 minutes??

Answer 22

no that is incorrect

please tell me how you got that answer

Answer 23

im not sure. i was trying solutions. Please carry on so i fully understand

Answer 24

guessing is bad, dont do it

anyways, remember how i said the time the car passes the truck is when they both travelled the same distance?

well if we know the distance travelled for the car is
d=72*t
and distance travelled for the truck is
d=12+60t

well this means that the "d"s are equal to each other and we can substitute

this gives us the equation
12+60t=72t

now solve for t

Answer 25

1=t

Answer 26

ok now remember that the answer is in hours

and its asking for minutes

1 hour = __ minutes?

Answer 27

incorrect?

Answer 28

oh crap its 71 mph not 72

Answer 29

change the 72 to a 71, recalculate it and then convert it to minutes

Answer 30

are you sure its not 35 minutes? o.o

Answer 31

yes im sure

Answer 32

12+60t=71t

solve for t, then multiply it by 60, and tell me what your answer is

Answer 33

sorry my net is being slow

Answer 34

you get 1... 1x60=60...

Answer 35

wait

Answer 36

no i changed the numbers....

Answer 37

11/12 x60 =55

Answer 38

12/11 im sorry

Answer 39

that should be your answer, assuming i didnt screw up else where and misread the problem

Answer 40

im sleepy. not the best time to do homework

Answer 41

is there a way to check and see if its 55?

Answer 42

yes, plug it into the 2 equation and see if the distances match

Answer 43

er, sort of, just remember i converted everythign into hours for the equations

Answer 44

it was 65. i just submitted.

Answer 45

12/11*60= 65.45454545...

Answer 46

got it correct :)

Answer 47

good for you